Stainless Steel ER309Cb
ER309Cb is a niobium-stabilized 23Cr-12Ni austenitic bare wire, used where a 309-type overlay or dissimilar joint must resist intergranular corrosion after thermal exposure.
Reference datasheet — ER309Cb is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the AW condition
ER309Cb tempers and conditions
ER309Cb is supplied in 3 conditions, soft to hard. AW is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As-welded submerged-arc / strip-cladding overlay deposit | Pick for high-deposition SAW wire or strip cladding of pressure-vessel steel; higher heat input gives slightly lower strength and toughness scatter. | 385 | 570 | 33 | 185 HB | 2.2 % IACS |
Post-weld heat treated | Use when the Cr-Mo or C-steel base metal mandates PWHT; Nb stabilization keeps the overlay resistant to sensitization, but some ferrite may transform toward sigma. | 400 | 580 | 30 | 195 HB | 2.2 % IACS |
AWDefault As-welded deposit | Standard condition for classification testing and most overlay/dissimilar-joint service — use unless PWHT is imposed by the base metal. | 410 | 600 | 35 | 190 HB | 2.2 % IACS |
Supply forms, finishes and certifications
Ways ER309Cb is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
WIRE | Cold-drawn bare filler wire/rod as supplied | Supply form |
What is ER309Cb?
ER309Cb is a niobium-stabilized 23Cr-12Ni austenitic bare wire, used where a 309-type overlay or dissimilar joint must resist intergranular corrosion after thermal exposure. The niobium ties up carbon, making it the usual buffer layer under 347 or 321 weld metal and before nickel-alloy cover passes. As-welded deposits give about 410 MPa yield, 600 MPa tensile, 35% elongation and 190 HB (90 HRB), with service to 800 °C and a corrosion rating of 68. Where stabilization is not required, ER309L is cheaper and more widely stocked. ER309Cb has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F). ER309Cb has a yield strength of 410 MPa (59.5 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 60% of stainless steel grades. Elongation at break is 35% and the elastic modulus is 196 GPa (28.4 Msi).
What is ER309Cb used for?
- Stabilized cladding and weld overlays
- Buffer layers under 347 or 321 weld metal
- Dissimilar-metal joints requiring Nb stabilization
- Transition welds ahead of nickel-alloy cover passes
- Submerged-arc overlay of pressure vessel shells
- Repair of stabilized stainless-clad equipment
- Refinery and petrochemical dissimilar piping welds
Advantages
- Readily welded — 88/100, better than 91% of stainless steel grades
Limitations
- Hard to polish — 60/100, worse than 80% of stainless steel grades
ER309Cb properties
Typical room-temperature values for ER309Cb-AW; bars are the position among stainless steel grades.
Physical3
ER309Cb has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
ER309Cb has a yield strength of 410 MPa (59.5 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 60% of stainless steel grades. Elongation at break is 35% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
ER309Cb is rated for continuous service to 800°C (1,472 °F). It conducts heat at 15 W/m·K (8.67 BTU/hr·ft·°F), worse than 59% of stainless steel grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
ER309Cb conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental2
Corrosion resistance is good (68/100), better than 63% of stainless steel grades.
Sustainability4
Producing a kilogram of ER309Cb takes about 55 MJ of energy and emits 4.8 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 55%.
Manufacturability7
ER309Cb's machinability is poor (32/100, worse than 62% of stainless steel grades); weldability excellent (88/100); formability good (55/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. ER309Cb is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ER309Cb
Is ER309Cb easy to machine?
Overlay machines like Type 309/347: low speed, heavy positive-rake carbide, rigid setup and flood coolant to fight work hardening and gumming.
Can ER309Cb be welded?
Run GTAW/GMAW/SAW with Ar or Ar+2%CO2 (or 100% Ar + He for TIG), interpass ≤150 °C and limited heat input to hold ferrite and avoid hot cracking; ideal buffer layer under 347/321 or before nickel-alloy cover passes.
Can ER309Cb be formed, bent or molded?
Supplied as cold-drawn wire; bend TIG rods only gently — the deposit itself work-hardens rapidly and is normally not cold formed.
ER309Cb chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C≤0.03 for the low-carbon ER309LNb variant | ≤ 0.12 | 0.06 |
| Cr | 23 – 25 | 24 |
| Ni | 12 – 14 | 13 |
| NbNb+Ta reported as Cb; stabilizing addition | 0.7 – 1 | 0.85 |
| Mn | 1 – 2.5 | 1.8 |
| SiSi-enhanced ER309LNbSi types run 0.65–1.00 | 0.3 – 0.65 | 0.45 |
| Moresidual | ≤ 0.75 | |
| Curesidual | ≤ 0.75 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on ER309Cb?
Grind, pickle and passivate the overlay to restore the passive film; avoid carbon-steel tooling contamination, no anodizing applies.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
How much does ER309Cb cost?
ER309Cb is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
ER309Cb — frequently asked
What is ER309Cb used for?
ER309Cb is typically used for stabilized cladding and weld overlays, buffer layers under 347 or 321 weld metal, dissimilar-metal joints requiring Nb stabilization, transition welds ahead of nickel-alloy cover passes, submerged-arc overlay of pressure vessel shells and repair of stabilized stainless-clad equipment. In short: stabilized 309 overlay wire; buffer layer for 347/321; resists intergranular attack.
What is the yield strength of ER309Cb?
ER309Cb has a typical yield strength of 410 MPa (59.5 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 60% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is ER309Cb easy to machine?
Not especially — machinability is rated poor (32/100, worse than 62% of stainless steel grades). Overlay machines like Type 309/347: low speed, heavy positive-rake carbide, rigid setup and flood coolant to fight work hardening and gumming.
Can ER309Cb be welded?
Yes — weldability is rated excellent (88/100). Run GTAW/GMAW/SAW with Ar or Ar+2%CO2 (or 100% Ar + He for TIG), interpass ≤150 °C and limited heat input to hold ferrite and avoid hot cracking; ideal buffer layer under 347/321 or before nickel-alloy cover passes.
What surface finishes work on ER309Cb?
Grind, pickle and passivate the overlay to restore the passive film; avoid carbon-steel tooling contamination, no anodizing applies.
Can ER309Cb be formed, bent or molded?
Supplied as cold-drawn wire; bend TIG rods only gently — the deposit itself work-hardens rapidly and is normally not cold formed.
What is the maximum service temperature of ER309Cb?
ER309Cb is rated for continuous use to about 800°C (1,472 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER309Cb-AW and ER309Cb AW-SAW?
AW is the default condition — standard condition for classification testing and most overlay/dissimilar-joint service — use unless PWHT is imposed by the base metal. AW-SAW: pick for high-deposition SAW wire or strip cladding of pressure-vessel steel; higher heat input gives slightly lower strength and toughness scatter. Yield strength is 410 MPa in AW versus 385 MPa in AW-SAW.
How much does ER309Cb cost?
ER309Cb is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- AWS A5.9/A5.9M — Bare Stainless Steel Welding Electrodes and Rods — American Welding Society (2017)
- ASM Handbook Vol. 6 — Welding, Brazing and Soldering — ASM International (1993)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels — ASM International (1990)
- Stainless filler metal datasheets (309/309LNb class) — Böhler Welding / Sandvik / ESAB (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.